무용기 용융법으로 제조한 Ba(Ti1-xZrx)2O5의 유리안정성 및 국부구조

초록

Containerless levitation techniques have been developed to avoid chemical contamination and heterogeneous nucleation by the container. These techniques allow melt to achieve deep undercooling, and can be utilized for the development of a new functional metastable material. J. Yu et al.[1] developed a new ferroelectric material BaTi2O5 as bulk glass from melt by using containerless processing and studied the phase relationship between microstructure and ferroelectric properties of BaTi2O5. They reported that amorphous BaTi2O5 shows giant permittivity (~107) at crystallization onset temperature of metastable α-BaTi2O5. Moreover, the BaTi2O5 glass represented a high refractive index of 2.2. Therefore, it can be utilized for high-performance optical lens, etc. Colorless transparent BaTi2O5 glass could not be prepared by conventional glass-making process via melt-quenching due to its poor glass forming ability. Aerodynamic levitation technology can lead to novel way of developing BaTi2O5 glass. Nevertheless, it is difficult to fabricate large-sized BaTi2O5 glass due to devitrification and crystallization. In this study, we produce BaTi2O5 with ZrO2 addition to enhance the glass forming ability. The ZrO2 can act as either a glass former, with a cation coordination number of 6 (octahedral ZrO6), or an intermediate oxide, with a coordination number of 8 (dodecahedral ZrO8). The microstructure and permittivity of BaTi2O5 and Ba(Ti,Zr)2O5 were investigated. Also, the Ti K-edge X-ray absorption florescence spectroscopy (XAFS) spectra of BaTi2O5 system were also collected in order to understand the local structure around Ti4+ ions when Zr4+ is substituted into Ti4+ sites.